regex from grandparent folder name

Question

I have a path like this C:\Users\Administrator\Desktop\Photos-or\3-PRO\3-1-CR\CR-RESTS\LES-COQS\1920x500 and I'd like a regex to match the grandparent folder which, in this case, is LES-COQS.

I've tried:

echo "C:\Users\Administrator\Desktop\Photos-or\3-PRO\3-1-CR\CR-RESTS\LES-COQS\1920x500" | grep -i "[a-zA-Z0-9-]*\\\[0-9a-z]*$"

Should I use a lookahead/lookbehind ? Or is there a simpler way ?

Thanks

Answer 1

Assuming you want to output the second-last component of that MS-DOS-style path, you could do:

msdos_path='C:\Users\Administrator\Desktop\Photos-or\3-PRO\3-1-CR\CR-RESTS\LES-COQS\1920x500'
expr "\\$msdos_path" : '.*\\\(.*\)\\.*'

Which here would output LES-COQS.

Answer 2

There are many ways to extract the penultimate item from the path. Here are a few with a mix of solution approaches

p='C:\Users\Administrator\Desktop\Photos-or\3-PRO\3-1-CR\CR-RESTS\LES-COQS\1920x500'

echo "$p" | grep -oP '.*\\\K[^\\]*(?=\\[^\\]+)'     # PCRE
echo "$p" | sed 's!^.*\\\([^\\]*\)\\[^\\]*$!\1!'    # RE

echo "$p" | awk -F'\\' '{print $(NF-1)}'            # Awk

IFS='\\' ps=($p); echo "${ps[-2]}"                  # Shell (bash)
px="${p%\\*}"; echo "${px##*\\}"                    # Shell

The expressions are much harder to read due to each backslash in the Windows folder path having to be matched by a double backslash in each RE pattern. (In fact, I worked on a couple of these by replacing \ with / throughout.)

Answer 3

May be this will help you to get the expected result

#!/bin/bash
# GNU bash, version 4.4.20
echo "C:\Users\Administrator\Desktop\Photos-or\3-PRO\3-1-CR\CR-RESTS\LES-COQS\1920x500" | rev | awk -F'\' '{ print $2 }' | rev

Output :

LES-COQS

Tested on : https://rextester.com/l/bash_online_compiler

Answer 4

You can use sed with extended regular expression and the substitution command:

$ echo "C:\Users\Administrator\Desktop\Photos-or\3-PRO\3-1-CR\CR-RESTS\LES-COQS\1920x500" | sed -E 's/(.*\\)([^\\]+)(\\[^\\]+)/\2/'
LES-COQS